Another line of thought..... cause I'm having second thoughts about the over fueling thing. Does the ZD30 have oil squirters under the pistons? How is the bore and rings lubricated on the ZD30 motor?

Just thinking that a lack of lubrication on the bore and rings causing excess heat and heat seize. That piston doesn't look burnt like mine did, yes the shape of the pistons is very different to the TD42's but look at the edges of the piston. Yes they look a little banged up, but not really melted. Look at the piston damage on my piston when I burnt a hole through it.....viewtopic.php?f=44&t=1266&hilit=burnt+hole#p11167

That ZD piston looks more scratched with "square" edges. On my photos the TD piston has rounded edges where it burnt away or melted.

1. The Injectors, the ZD 30 uses normal injectors, not the electronic ones. so I will have them tested as a precaution.
2. Lubrication, This was my first thought as well, but I removed the nozzle and it is clean and wide open.
3. I will strip the intake manifold of this afternoon to check the valve intake.

From my personal experience, piston crown failure (which looks to be the case here)is caused by overheating of the piston, this is in line with all your thoughts, so now we just have to establish the cause of the overheating on this piston.

I'm still inclined to say that the heating wasn't from fuel burning or combustion heat, but more a lack of oil, or possibly water coolant not flowing properly.

What was the coolant water looking like? Rusty or a good antifreeze colour? Antifreeze can also be a bugger. A lot of the cheaper brands have a high hydrochloric acid concentration, which can eat away the block, so dilution levels have to be spot on. I am a firm believer in expensive coolant/antifreeze, or the genuine Nissan stuff. This was conveyed to me by Frans ( Tour de Frans ) many many many times!!!! Do any of the water ports look blocked? Could there have been a blocked water port preventing cooling around the no 1 cylinder?

I suppose checking for a blockage would be almost impossible other than trying to blast water into the ports.... but that would probably blast any obstruction out of the channels inside the block.... :confused: :confused:

Hi Guys,to all our diesel fanatics out there
The first sign of the injectors starting to play up ,is when you park your car at nite and the next morning you start it up and there is the rough coughing and white smoke and clattering of the engine....
the injectors cant hold its required pressures and it starts to leak RAW fuel onto the piston ,in doing so it also washes all lubrication of the cylinders . so when you want to start your engine in the morning,
the compression has now doubled because of raw diesel that leak through injector is now lying on top of piston and the friction of the piston is increased against the cleaned cylinder.
the crown of the piston takes the knock and starts to get hairline cracks which needless to say eventually lets go .
It pays to have those injectors calibrated and tested every 80 000- 100 000km

Thanks for that Wilkie. I've done just over 305000km on my 2002 Hardbody ZD30. She hasn't given me any major problems - had the turbo serviced once.

Perhaps the issues she's been such an old faithful is because she's been superslow going up hills for as long as I can remember. My 4.2D GQ does better on some hills than her - and that says a LOT. So instead of waiting for any grenades to go boom, I'll get those injectors calibrated and tested. Anything else I should do or look out for chaps? I'm about to do an oil analysis for the first time. Very curious to see what that picks up (but of course it's the next couple of analyses that will really shed some light).

Its easier and probably cheaper to just recon the injector tips on a TD42. The last time I did mine they were R425 each ( x6 ), and super easy to replace. Just be VERY careful with the diesel spill rail. The little pipes on there break very easily if the get twisted !!!